 |
| Anatomy of a Typical Monocot Root |
|
| |
| Example : Maize |
| |
| A transverse section passing through the Maize root reveals the following details. |
| |
| Epiblema |
| |
| Epiblema is the outermost covering of the root formed by a single layer of compactly arranged, barrel-shaped parenchyma cells. The cells are characteristically thin-walled since they are involved in absorption of water. A cuticle and stomata are absent. Some of the epiblema cells are produced into long unicellular projections called root hairs. Hence, epiblema is also known as piliferous layer. |
| |
 |
| |
| T.S. of a Monocot Root |
| |
 |
| |
| Cross-Section of a Monocot Root |
| |
| Cortex |
| |
| Cortex is a major component of the ground tissue of root. It is represented by several layers of loosely arranged parenchyma cells. Intercellular spaces are prominent. The cortex is mainly meant for storage of water. The cells also allow a free movement of water into the xylem vessels. |
| |
| Endodermis |
| |
| It is the innermost layer of cortex formed by compactly arranged barrel-shaped cells. Some of the cells in the endodermis are thin-walled and are known as passage cells. The passage cells allow water to pass into the xylem vessels. The remaining cells in the endodermis are characterised by the presence of thickening on their radial walls. These thickenings are known as casparian thickenings. They are formed by the deposition of a waxy substance called suberin. The casparian thickenings play an important role in creating and maintaining a physical force called root pressure. |
| |
| Stele |
| |
| Stele is the central cylinder of the root consisting of pericycle, conjunctive tissue, pith and vascular bundles. |
| |
| Pericycle |
| |
| Pericycle is the outermost covering of the stele represented by a single layer of parenchyma cells. |
| |
| Conjunctive tissue |
| |
| It is represented by loosely arranged parenchyma cells found in between the vascular bundles. The cells are specialized for storage of water. |
| |
| Pith |
| |
| Pith is the innermost region of the root representing the central axis. It is composed of few loosely arranged parenchyma cells. |
| |
| Vascular bundles |
| |
| Vascular bundles are radial in arrangement. There are eight bundles each of xylem and phloem. Hence, the condition is described as polyarch. Xylem is described as exarch. |
| |
|
 |
| |
